Agriculture Reference
In-Depth Information
Table 5.3 Comparison of North American regions with mediterranean-type vegetation comprising chaparral
shrublands, in California with a MTC, and Arizona and northeastern mainland Mexico with non-MTCs
Sierra Madre
Oriental, Mexico
California
Arizona
Total extent (1000 ha)
7565
1214
100
Latitude
30-40N
30-34N
16-20N
Longitude
117-123W
108-115W
97-101W
Elevation range (m)
100-2000
900-2400
2000-2800
Mean daily temperature
range (
C)
7-27
0-33
11-17
Annual precipitation (mm)
275-675
250-650
380-640
Precipitation distribution
Winter to early
spring
Winter to early spring and
mid to late summer
Summer
Water deficit (evap
ppt)
Late spring to early
autumn
Late spring to early
summer and mid
to late autumn
Winter to spring
>
Percentage shrubs evergreen
95%
75%
50%
>
Number of shrub species in
common with California
-
11
4
Woody plant diversity
Two highly diverse
genera
No highly speciated
woody genera
No highly speciated
woody genera
Annuals
Highly diverse
Pretty diverse
Little diversity
C
4
grasses
Non-existent
Very diverse
Very diverse
Postfire shrub recovery
Sprouting and
seedlings
Sprouting and seedlings
Sprouting and
seedlings
Herbaceous postfire
Diverse spring
postfire annual
flora
Postfire ephemeral flora
comprises two seasonal
floras: spring and
autumn
Only a summer
postfire flora
Arizona chaparral shares many shrub species with California, including
Arctos-
taphylos pringlei
,
A. pungens
,
Ceanothus greggii
,
Cercocarpus betuloides
,
Eriogonum
fasciculatum
,
Garrya flavescens
,
Quercus turbinella
,
Rhamnus californica
,
R. crocea
,
Rhus ovata
, and
R. trilobata
. The islands of chaparral in the Sierra Madre Oriental
of northeastern Mexico share only four of these species but also have closely
related species in several other genera.
Despite the sharing of shrub dominants, these non-MTC chaparrals comprise
very different plant communities. This largely derives from the difference in
growing seasons. In contrast to California, Mexican chaparral has a warm grow-
ing season and as a result the herbaceous understory and postfire flora comprise
fewer annuals and many C
4
perennial grasses (Shreve
1939
). Arizona chaparral,
with a bimodal pattern of rainfall, comprises elements of both Californian and
northeastern Mexican chaparral. This disparity is particularly evident after fire in
Arizona, where the postfire ephemeral flora comprises a spring flora of annuals
and an autumn flora dominated by herbaceous perennials (Fotheringham
2009
).
